Operating device for electric switching apparatus for high voltage

ABSTRACT

In an operating system for high voltage gas blast circuit breakers, the opening impulse is transmitted from earth to high potential by means of an insulating tension rod. A high initial acceleration of the rod is obtained by means of an electrodynamic operating device positioned at the lower end of the rod. This operating device comprises a stationary coil and an operating plate connected inductively to the coil and directly joined to the tension rod.

United States Patent Berneryd et a].

[ Oct, 17, 1972 OPERATING DEVICE FOR ELECTRIC SWITCHING APPARATUS FORHIGH VOLTAGE Inventors: Sten Berneryd; Hans Backskog, both of Ludvika,Sweden Assignee: Allrnanna Svenska Elektriska Ak- V tiebolaget,Vasteras, Sweden Filed: Sept. 20,1971

Appl. No.: 181,872

Foreign Application Priority Data Oct. 2, 1970 Sweden ..l3378/70 U.S.Cl. ..200/148 R Int. Cl. .t ..H0lh 33/42 Field of Search ..200/148 B,148 R [56] References Cited UNITED STATES PATENTS 3,256,414 6/1966Giammona et a1. ....200/l48 B 3,420,972 1/1969 Pucher ..200/148 R3,532,843 10/1970 Pucher .;..200/l48B Primary Examiner-Robert S. MaconAtt0mey Jennings Bailey, Jr.

[57] ABSTRACT 9 Claims, 2 Drawing Figures PATENTEnnm 1 1v m2 srzwBER/vamp BY HANS @MLKSKQG OPERATING DEVICE FOR ELECTRIC SWITCHINGAPPARATUS FOR HIGH VOLTAGE RELATED APPLICATIONS This application isrelated to US. application, Ser. No. l4l,l74, filed May 7, 1971, whichshows an operating system in which some features are common with thepresent invention.

BACKGROUND OF THE INVENTION 1. Field of the Invention The presentinvention relates to a means for operating at least one contact in anelectric switching device for high voltage and relates primarily tovoltages of the order of 1,000 kilovolts. The means is of the type inwhich a movement impulse is rapidly transferred from earth to highpotential through a tension rod.

2. The Prior Art In the operation of switching devices forextremely highvoltages, very short and exact switching times are required. This can beachieved as proposed in application, Ser. No. 883,134 to Grune et al.filed Dec. 8, 1969, by using electro-dynamically operated pneumaticoperating members placed in the immediate vicinity of the contacts athigh potential and arranging release of the operating members fromearthpotential by means of an electro-optical signal transmission system. Insuch an arrangement, the operating energy for the electro-dynami'csystem must be accessible at high potential. However, it has been foundboth difficult and expensive to arrange the supply of this energysatisfactorily. Such an energy feeding system is not necessary if aninsulating tension rod is used to transfer the required impulses from anoperating member placed at earth potential to a pressurized gas valveplaced at high potential to operate the contactsfln a previously knownconstruction of this type (US. Pat. No. 3,420,972), the. movement of therod is effected by supplying pressurized gas to a cylinder space inwhich an operating piston joined to the lower end of the rod is axiallydisplaceable. The initial acceleration which can be imparted to the rodin this construction is insufficient for circuit breakers for very highvoltages, and it is also difficult to regulate the speed of the rod as afunction of the time. The possibility of this is particularly desirablewhen the rod is to be used to transmit impulses to both a powerinterrupter contact and a resistor interrupter contact with a certaintime delay between the impulses.

SUMMARY OF THE INVENTION The object of the present invention is toeffect an operating means which in the above respects is more suitablethan corresponding previously known constructions.

As in the embodiment shown in patent Ser. No. 3,420,972, the operatingmeans according to the present invention comprises a pressurized gasvalve placed in the vicinity of the contacts of the switching device athigh potential, the movable valve member being controlled from earthpotential by means of an insulating tension rod arranged inside asupport insulator filled with compressed gas, the tension rod beingjoined to two pistons which are axially displaceable along cylindricalsurfaces at the upper and lower ends of the rod, the upper side of theupper piston being in communication with the open air. The invention ischaracterized in that the tension rod is arranged upon operation of thecontacts to be moved in downward direction from an upper end position inwhich the upper side of the lower piston lies in sealing abutment withone valve seat and is thus influenced by the pressurized gas in thesupport insulator on a surface which is smaller than the surface of theupper piston, whereas, when said lower piston is lifted from its seatupon operation of the switching device, it is influenced by thepressurized gas over its entire surface, which is greater than thesurface of the upper piston, an electrodynamic operating device beingarranged at the lower end of the tension rod to operate the switchingdevice, the electro-dynamic device consisting of a stationary coil andan operating plate connected inductively. to the coil and joined to thetension rod. Since the operating plate in the electro-dynamic operatingsystem is attached directly to the tension rod an extremely quickinitial acceleration of the rod is achieved. Since also the entiresurface of the piston is immediately influenced by the pressurized gaswhen the piston is lifted from its seat, the quick movement willcontinue even after the electro-dynamic force has disappeared.

The operating device may suitably be designed so that the lower pistonalso acts as operating plate, in which case a separate plate is notnecessary. This involves a considerable simplification.

Switching apparatus of the type in question are usually designed forautomatic rapid re-closing and it is thus desirable for the tension rodto be quickly returned to its initial position after operation. This caneasily be achieved by means of a valve plate joined by a spring to thelower piston and closing the outlet opening from a cylinder chamberarranged under the lower piston. At the final stage of the openingmovement pressurized gas is supplied to this cylindr chamber from theupper side of the piston through a pressure equalizing channel.

In certain switching devices it is necessary to supply power impulses toat least two contacts with a certain time delay between the impulses,but with a common .release signal. For this purpose, the deviceaccording to the invention can be designed so that at least twopneumatic valves at high potential are arranged to 'be influenced by anumber of cams supported by the tension rod. Suitable time delay betweenthe release impulses to the various contacts can thus easily be adjustedby attaching the cams to the rod in such a way that the distance betweenthem can be altered.

In order to achieve exact intervals between the various releaseimpulses, it is desirable for the movement of the tension rod to be keptsubstantially constant after the first rapid acceleration. This can beachieved by reducing the driving force on the tension rod after acertain time, which can be realized relatively easily by means of adamping piston, as is clear from the following description BRIEFDESCRIPTION OF THE DRAWINGS The drawings show an embodiment of theinvention,

FIG. 1 showing the principle for transmission of the release impulsesfrom earth to high potential, while,

FIG. 2 shows the operating member arranged at earth potential in closerdetail.

FIG. 1 shows schematically two pneumatic valves 1 and 2 placed at highpotential and intended while emit power impulses to a power contact anda resistor contact, respectively, in an electric switching device, forexample an air blast circuit breaker. The valves are shown in theirnormal positions in which the pneumatic operating mechanism of thecontacts, not shown, is in communication with the open air through twoconduits 3 and 4 and outlet channels 5 and 6. Release of the contacts iseffected by opening the valves 1 and 2 so that the two conduits 3 and 4are placed under pressure from a hollow support insulator 7 filled withpressurized gas and is fed by a conduit 8 from a source of pressurizedgas arranged at earth potential. The valves 1 and 2 are opened by twocams 9 and 10 which are attached to a vertical tension rod 11 ofinsulating material arranged inside the support insulator 7 which rod isprovided at its upper end with a piston 12 and at its lower end with apiston 13 having a larger diameter than the piston 12. The pistons areaxially displaceable along cylindrical surfaces 14 and 15 at the upperand lower ends of the rod. Between the pistons and the cylindricalsurfaces are sealing rings. The lower side of the lower piston 13 limitsa cylindrical space 16 which during normal operation is in communicationwith the open air through an axially arranged outlet opening 17.

In the position of rest of the switching device, the lower piston 13 ispressed against a valve seat 18 (FIG. 2) arranged on the upper side ofthe piston due to pressure on the piston 12 at the upper end of the rod.The switching device is operated by a previously charged capacity beingdischarged through an induction coil 19 arranged around the valve seat18 so that a current is induced in the piston 13 which is made ofmaterial having good electrical conductivity, for example aluminium, orhas a short-circuiting ring made of such material. As a result thepiston 13 is pushed away from the valve seat 18 with considerable force.The gas pressure in the support insulator 7 then operates over theentire surface of the piston 13 so that the movement continues evenafter the force coming from the electrodynamic operating device hasceased.

The tension rod 11 is returned when pressure equalization is achieved inthe cylindrical space 16 below the piston 13 through a by-pass flowchannel 20 after a valve plate 22 connected by a spring 21 to the piston13 has closed the outlet opening 17 to the atmosphere. When the piston13 has returned to the valve seat 18 the plate 22 is returned by thespring 21 since atmospheric pressure is reestablished in the cylinderspace 16 through an equalizing hole 23.

Instead of letting the piston 13 act as operating plate in theelectro-dynamic operating device, the electrodynamic and pnuematicfunctions can be separated by placing an induction coil 27 with aseparate operating plate 24 completely outside the cylinder space 16, asindicated by dotted lines in FIG. 2. The electro-dynamic system can thenmore easily be dimensioned so that greater operating power is obtained.Furthermore, a more favorable I'ield pattern is obtained around the coiland the efficiency of the system is thus improved.

In order to achieve an exact time interval between the release momentsof the contact devices controlled by the two valves 1 and 2 it isdesirable for the speed of the tension rod during the latter stage ofthe operating movement to be kept substantially constant. This can beachieved by throttling the opening 26 surrounded by the valve seat 18,with the help of a damping piston 25 on the tension rod 11. The supplyof blast air to the space above the piston 13 is thus closed off and thedownward driving force on the tension rod is reduced.

The invention is not limited to the embodiment shown. The tension rod11, for example, need not affect the contacts of the switching devicethrough camcontrolled pneumatic valves. Thus, the rod may be connectedto the contacts or made to operate the contacts in any other suitablemanner. The operating device may also be combined with conventionalmeans for damping and braking.

We claim:

1. Means for operating at least one contact in an electric switchingdevice for high voltage comprising a pneumatic valve (I) placed at highpotential, a hollow supportinsulator (7) adapted to be filled withcompressed gas carrying said pneumatic valve at its upper end, aninsulating tension rod (11) movable upward and downward within saidsupport insulator, means forming cylindrical surfaces (14,15) adjacentthe top and bottom of said support insulator, a valve passage betweenthe cylindrical surfaces having a valve seat, upper and lower pistonmeans (12,13) connected to said tension rod and slidable within saidcylindrical surfaces, the cross-sectional area of the lower piston meansbeing greater than that of the upper piston means, the cross-sectionalarea of the valve seat being less than that of the upper piston means,the top surface of the upper piston means being exposed to atmosphericpressure, means "for moving said tension rod downwardly from an upperend position in which the top surface of the lower piston means lies inscaling abutment with said valve seat (18) and is thus influenced by thepressurized gas in the support insulator on a part of its surface whichis smaller than the surface of said upper piston means, whereas, whensaid lower piston means is lifted from its seat upon operation of theswitching device, it is influenced by the pressurized gas over itsentire surface, said tension rod moving means comprising anelectro-dynamic operating device at the lower end of said tension rod tooperate the switching device, said electro-dynamic' operating devicecomprising a stationary coil and an operating plate means, said platemeans being connected inductively to said coil and joined to saidtension rod.

2. Means according to claim 1, in which the operating platemeansconstitutes the lower piston means.

3. Means according to claim 1, in which the cylindrical surface adjacentthe bottom of the support insulator encloses a cylindrical space belowthe lower piston means which is in communication with the open airthrough an axially arranged outlet opening (17).

4. Means according to claim 3, a spring carried by the lower piston onthe bottom side thereof, and a valve plate carried by the spring which,when the tension rod, upon operation of the switching device, has moveda certain distance from its upper end position, closes said outletopening.

5. Means according to claim 1, in which in the lower cylindrical surfacethere is at least one channel which, when the rod has moved a certaindistance, provides largement carried by the tension rod and movable intothe hole during downward movement of the rod to throttle the flow of gasfrom the interior of the support insulator into the space above thelower piston.

8. Means according to claim 1, including at least two pneumatic valves,cams on said tension rod engageable with said pneumatic valves.

9. Means according to claim 8, in which said cams are adjustably mountedon said tension rod.

1. Means for operating at least one contact in an electric switchingdevice for high voltage comprising a pneumatic valve (1) placed at highpotential, a hollow support insulator (7) adapted to be filled withcompressed gas carrying said pneumatic valve at its upper end, aninsuLating tension rod (11) movable upward and downward within saidsupport insulator, means forming cylindrical surfaces (14,15) adjacentthe top and bottom of said support insulator, a valve passage betweenthe cylindrical surfaces having a valve seat, upper and lower pistonmeans (12,13) connected to said tension rod and slidable within saidcylindrical surfaces, the cross-sectional area of the lower piston meansbeing greater than that of the upper piston means, the cross-sectionalarea of the valve seat being less than that of the upper piston means,the top surface of the upper piston means being exposed to atmosphericpressure, means for moving said tension rod downwardly from an upper endposition in which the top surface of the lower piston means lies insealing abutment with said valve seat (18) and is thus influenced by thepressurized gas in the support insulator on a part of its surface whichis smaller than the surface of said upper piston means, whereas, whensaid lower piston means is lifted from its seat upon operation of theswitching device, it is influenced by the pressurized gas over itsentire surface, said tension rod moving means comprising anelectro-dynamic operating device at the lower end of said tension rod tooperate the switching device, said electro-dynamic operating devicecomprising a stationary coil and an operating plate means, said platemeans being connected inductively to said coil and joined to saidtension rod.
 2. Means according to claim 1, in which the operating platemeans constitutes the lower piston means.
 3. Means according to claim 1,in which the cylindrical surface adjacent the bottom of the supportinsulator encloses a cylindrical space below the lower piston meanswhich is in communication with the open air through an axially arrangedoutlet opening (17).
 4. Means according to claim 3, a spring carried bythe lower piston on the bottom side thereof, and a valve plate carriedby the spring which, when the tension rod, upon operation of theswitching device, has moved a certain distance from its upper endposition, closes said outlet opening.
 5. Means according to claim 1, inwhich in the lower cylindrical surface there is at least one channelwhich, when the rod has moved a certain distance, provides equalizingcommunication between the two sides of the lower piston.
 6. Meansaccording to claim 3, in which the cylindrical space is provided with asmall opening (23) putting it in permanent communication with the openair.
 7. Means according to claim 1 having a wall adjacent and above thelower piston, said valve passage comprising a hole through said wall ofsubstantially greater cross-section than the cross-section of thetension rod, the tension rod passing through the hole, and anenlargement carried by the tension rod and movable into the hole duringdownward movement of the rod to throttle the flow of gas from theinterior of the support insulator into the space above the lower piston.8. Means according to claim 1, including at least two pneumatic valves,cams on said tension rod engageable with said pneumatic valves.
 9. Meansaccording to claim 8, in which said cams are adjustably mounted on saidtension rod.